Association of novel biomarkers with future cardiovascular events is influenced by ethnicity: results from a multi-ethnic cohort

BACKGROUND

We sought to define the influence of ethnicity on associations between novel biomarkers and cardiovascular disease (CVD) events among Multi-Ethnic Study of Atherosclerosis (MESA) study participants, a community based population of asymptomatic US adults.

METHODS

Baseline (log transformed) levels of biomarkers namely C-reactive protein (CRP), fibrinogen, interleukin-6 (IL-6), D-dimer, plasmin-antiplasmin complex (PAP) and factor VIII were used to predict the cumulative incidence of all CVD events in an ethnicity stratified study cohort from Cox-proportional hazard analysis where models were adjusted for relevant confounders.

RESULTS

Ethnic cohorts included 2362 Caucasians, 1601 African Americans, 1353 Hispanics, and 751 Chinese. At mean 4.6 years of follow-up, 286 CVD events were identified with cumulative incidence of 11.3% in Caucasians, 9.8% in African Americans, 11.3% in Hispanics and 6.9% in Chinese. Biomarker risk association with CVD events incidence was significantly influenced by ethnicity with positive association (HR, 95% CI, p value) being shown for: CRP among Caucasians only (1.23, 1.04-1.47, <0.01) IL-6 among African Americans only (1.69, 1.15-2.48, <0.01) and fibrinogen among Caucasians (3.05, 1.21-7.69, 0.02), African Americans (3.51, 1.09-11.2, 0.03) and Hispanics (4.16, 1.23-14.1, 0.02) only. None of the biomarkers were able to predict CVD in Chinese. Association between above biomarkers and CVD was bi-directional: cases with CVD events had higher mean levels of biomarkers; cases in higher quartiles of biomarkers had increased cumulative incidence of CVD events.

CONCLUSION

Study results from a vast, ethnically diverse, asymptomatic US adult population suggest that biomarker association with incident CVD events is significantly influenced by ethnicity.

Two-dimensional strain profiles in patients with physiological and pathological hypertrophy and preserved left ventricular systolic function: a comparative analyses

OBJECTIVE

This study was designed to examine the utility of two-dimensional strain (2DS) or speckle tracking imaging to typify functional adaptations of the left ventricle in variant forms of left ventricular hypertrophy (LVH).

DESIGN

Cross-sectional study.

SETTING

Urban tertiary care academic medical centres.

PARTICIPANTS

A total of 129 subjects, 56 with hypertrophic cardiomyopathy (HCM), 34 with hypertensive left ventricular hypertrophy (H-LVH), 27 professional athletes with LVH (AT-LVH) and 12 healthy controls in sinus rhythm with preserved left ventricular systolic function.

METHODS

Conventional echocardiographic and tissue Doppler examinations were performed in all study subjects. Bi-dimensional acquisitions were analysed to map longitudinal systolic strain (automated function imaging, AFI, GE Healthcare, Waukesha, Wisconsin, USA) from apical views.

RESULTS

Subjects with HCM had significantly lower regional and average global peak longitudinal systolic strain (GLS-avg) compared with controls and other forms of LVH. Strain dispersion index, a measure of regional contractile heterogeneity, was higher in HCM compared with the rest of the groups. On receiver operator characteristics analysis, GLS-avg had excellent discriminatory ability to distinguish HCM from H-LVH area under curve (AUC) (0.893, p<0.001) or AT-LVH AUC (0.920, p<0.001). Tissue Doppler and LV morphological parameters were better suited to differentiate the athlete heart from HCM.

CONCLUSIONS

2DS (AFI) allows rapid characterisation of regional and global systolic function and may have the potential to differentiate HCM from variant forms of LVH.

Abstract P236: Relationship Between Red Cell Distribution Width and Alcohol Intake: An Analysis of the NHANES, 1999 to 2006

Introduction: Moderate alcohol intake has been associated with reduced cardiovascular mortality. Red cell distribution width (RDW) is an emerging cardiovascular risk marker, that is increasingly gaining recognition. No prior study has evaluated the association between alcohol intake and RDW.

Methods: We evaluated 6,424 nationally representative individuals participating in the National Health and Nutrition Examination Survey (NHANES) 1999 to 2006, free of cardiovascular co-morbidities (including coronary heart disease, diabetes, congestive heart failure, stroke and myocardial infarction) at baseline. RDW was divided into quartiles [Quartile 1 (Q1) ≤12 (reference category), Q2: 12.1-12.5; Q3: 12.6-13; Q4: >13] and alcohol intake was categorized by number of drinks per day [<1 drink/day, reference category), 1 drink/day, 2 drinks/day and ≥3 drinks/day]. Multivariate adjusted logistic regression analysis was performed to evaluate the risk relationship between RDW levels and daily alcohol intake.

Results: Mean RDW levels varied inversely with number of drinks per day (12.9 in reference alcohol category versus 12.5 in ≥3 drinks/day, p<0.001). Results of multivariate adjusted logistic regression analysis are shown in Table 1.

Conclusion: Moderate alcohol intake [1 to 2 drinks /day] is associated with more favorable levels of RDW. The association appears to be independent of nutritional deficiencies, inflammatory markers and other conventional cardiovascular risk factors.

Table 1:

Abstract P351: Ethnic Differences in the Risk Estimates of Novel Biomarkers for Future Cardiovascular Outcomes

Background: Elevated inflammatory markers, haemostatic factors as well as homocysteine predict cardiovascular disease (CVD) events and mortality. Although racial/ethnic disparities in CVD risk factors and outcomes exist, comparative data on the predictive utility of novel biomarkers for future CVD events in US ethnic groups is limited.

Methods: The study comprised 6814 asymptomatic men and women (52.85%), aged 45-84 yrs without prior cardiovascular disease, enrolled in the Multi-Ethnic Study of Atherosclerosis [MESA] obtained from NHLBI Data repository. 6270 asymptomatic men and women [1384 Hispanics, 2409 Caucasians, 753 Chinese and 1724 African Americans] with a host of novel biomarkers drawn were considered for this analysis. The CVD events were defined as ALL CVD events and HARD CVD events per MESA protocol (see Table).

Results: A total of 302 all CVD events and 203 hard CVD events were identified during a mean follow up of 4.6 years. We observed significant ethnic differences in the prognostic utility of novel biomarkers for cardiovascular risk assessment, in a large multi-ethnic population of US adults free of clinical cardiovascular disease. While homocysteine emerged as a robust biomarker across racial cohorts, most other biomarkers analyzed predominantly predicted events in Caucasians (see Table).

Conclusion: These findings raise serious concern about the prognostic potential or generalizability of risk stratification tools across racial subsets and underscore the need for further ethnicity-specific research in this area.

Abstract P185: Metabolic Syndrome and Cardiovascular Risk - A Comparative Analysis of Waist-Cricumference and Waist-Height-Ratio for Predictive Accuracy

Introduction: Metabolic syndrome (MS) is an adverse predictor of cardiovascular outcomes. Recently, waist height ratio (WHtR) is shown to correlate better with future cardiovascular risk factors than other anthropometric measures. We sought to determine whether replacing waist circumference (WC) with WHtR in metabolic syndrome diagnostic criteria per National Cholesterol Education Program (NCEP) guidelines improves predictive accuracy for future cardiovascular disease (CVD) events.

Methods: The study cohort consisted of prospectively evaluated 6,702 healthy adults aged 45-84 years enrolled in the Multi-Ethnic Study of Atherosclerosis [MESA] study [Age-: 62±10 years, 47% males, 1473 Hispanics, 2575 Caucasians, 799 Chinese and 1855 African Americans]. Metabolic syndrome (MSwc), at baseline, was defined by NCEP guidelines (n=2,208). Metabolic syndrome (MSwhtr) was redefined using WHtR (≥ 0.5 in both male and females) in place of WC, keeping rest of the components constant as recommended by NCEP (n=2,590). CVD events were defined as All CVD (CVDa) per MESA protocol (See Table ). Unadjusted and adjusted Cox-proportional hazard analysis was performed. Harrell's C-statistics were calculated for the most adjusted models.

Results: Total of 319 CVDa events [n=171 (7.44%) in MSwc group and n=190 (7.34%) in MSwhtr group] were identified during a mean follow up of 4.6 years. Results are displayed in the table .

Conclusion: Predictive accuracy of MS re-defined with WHtR and MS defined with WC per NCEP criteria is comparable.

Predictors of residual cardiovascular risk in patients on statin therapy for primary prevention

BACKGROUND

Low-density lipoprotein cholesterol-lowering therapy is an important aspect of primary prevention of cardiovascular disease (CVD). Statins are the most widely used drug therapy for achieving low-density lipoprotein goals based on an individual's 10-year risk. However, substantial risk of CVD events still exists even when a person is on statins. We sought to explore the predictors of future CVD events in individuals on statins with no pre-existing CVD.

METHODS

The analysis was done on subjects who were on statins (n = 919) at baseline in the Multi-Ethnic Study of Atherosclerosis limited access dataset from the National Heart, Lung and Blood Institute. The primary outcome variable was all-cause CVD events (n = 67). Multivariate regression Cox proportional hazard analysis was done to identify potential independent predictors of all-cause CVD.

RESULTS

Our cohort consisted of 47% males, with a mean age of 66 ± 9 years. Sixty-seven participants (7.3%) experienced CVD events during a mean follow-up of 4.4 years. A higher coronary artery calcium score, homocysteine levels, waist circumference and a lower large arterial elasticity index were identified as independent predictors of CVD events.

CONCLUSION

Homocysteine, waist circumference, coronary artery calcification and the large artery elasticity index appear to be the major independent predictors of CVD events in individuals on statins with no pre-existing CVD. In addition to emphasizing weight loss, alternative approaches beyond lipid reduction may need to be explored to better characterize and attenuate the residual risk in subjects on statin therapy for primary prevention.

Traditional cardiovascular risk factors and severity of angiographic coronary artery disease in the elderly

Over 80% of annual coronary heart disease mortality occurs in the elderly, a rapidly expanding subset of the population. The authors retrospectively examined the relationship between traditional cardiovascular risk factors and atherosclerotic coronary artery disease burden in a cohort of 631 elderly patients undergoing angiography. Age and male sex but not hypertension or dyslipidemia were predictors of presence of obstructive coronary artery disease (Duke score >or=2). Only diabetes mellitus emerged as an independent predictor of obstructive coronary artery disease burden. Smoking was found to be predictive of left main coronary artery disease. In summary, severity of angiographic disease in the elderly as assessed by Duke Myocardial Jeopardy scoring appears to correlate poorly with prevalence of established traditional cardiovascular risk factors.

Red cell distribution width and risk of coronary heart disease events

Red cell distribution width (RDW) has emerged as a powerful predictor of all-cause mortality in variety of cardiovascular settings. However, no data are available associating RDW with coronary heart disease (CHD) risk in a healthy and nationally representative multiethnic population. A total of 7,556 participants of the National Health and Nutrition Examination Surveys 1999 to 2006 (age 41.5 ± 15.8 years, 60% women) were divided into 3 categories according to their 10-year Framingham risk of hard CHD events: <10% (n = 6,173, reference category), 10% to 20% (n = 1,093, intermediate-risk category), and >20% (n = 290, high-risk category). Unadjusted and adjusted multivariate logistic regression analyses were performed evaluating RDW as a predictor of CHD risk. Each unit increase (0.1) in RDW posed a statistically significant greater odds of being in the intermediate-risk category (odds ratio -1.35, 95% confidence interval 1.27 to 1.45, p <0.001) and high-risk category (odds ratio -1.38, 95% confidence interval 1.25 to 1.53, p <0.001) compared to the reference category, after adjusting for race, body mass index, estimated glomerular filtration rate, hemoglobin A1c, C-reactive protein, hemoglobin, and mean corpuscular volume. Additional adjustments with serum iron, vitamin B(12), and folic acid levels did not affect the association. Subsequently, we divided participants into 2 categories according to their anemia status (as defined by the World Health Organization) to evaluate its effect. An RDW level greater than the seventy-fifth percentile in both anemic and nonanemic participants was a significant predictor of greater CHD risk while RDW of the seventy-fifth percentile or less in anemic participants failed to predict CHD (compared to nonanemic participants with similar RDW as the reference category). In conclusion, a higher RDW appears to be a powerful independent predictor of future CHD risk.

Global and regional left ventricular contractile impairment in patients with wolff-Parkinson-white syndrome

BACKGROUND

To assess regional systolic function and global contractile function in patients with WPW Syndrome.

METHOD

Eleven cases with manifest Wolff-Parkinson-White (WPW) syndrome in sinus rhythm were compared to 11 age matched controls. 2D strain analysis was performed and peak segmental radial strain (pRS) values obtained from basal ventricular parasternal short-axis images (70 +/- 5 frames/sec) using a dedicated software package. Heterogeneity of radial strain pattern in six circumferential basal left ventricular segments was measured in terms of standard deviations of peak RS (SD(pRS)) or range (difference between maximum and minimum peak RS i.e. Range(pRS)). Spectral Doppler (continuous wave) measurements were acquired through the left ventricular outflow tract to determine Pre Ejection Period (PEP), Left Ventricular Ejection Time (LVET) and measures of left ventricular systolic performance.

RESULTS

LV segmental radial strain was profoundly heterogeneous in WPW cases in contrast to fairly homogenous strain pattern in normal subjects. Wide SD(pRS) values 17.5 +/- 8.9 vs 3.3 +/- 1.4, p<0.001 and Range(pRS) 42.7 +/- 20.8 vs.8.5 +/- 3.6 , p<0.001 were observed among WPW and healthy subjects respectively. PEP (132.4 +/- 14.7 vs 4.7 +/- 0.5ms, p<0.001) and corrected PEP (76.1 +/- 8.0 vs 2.7 +/- 0.4ms, p<0.001) were significantly longer in WPW patients compared to controls. The PEP/LVET ratio was also significantly greater in WPW cohort (0.49 +/- 0.04 vs. 0.28 +/- 0.05, p <0.001) suggesting global systolic dysfunction.

CONCLUSIONS

Patients with manifest preexcitation (predominantly those with right-sided pathways) have regional and global contractile dysfunction resulting from aberrant impulse propagation inherent to the preexcited state.

Comparison of five-year outcome in African Americans versus Caucasians following percutaneous coronary intervention

BACKGROUND

Studies regarding short-term outcomes after percutaneous coronary intervention (PCI) have reported no ethnic differences and data on long-term follow-up is conflicting and sparse.

METHODS

730 consecutive patients (67% African American) undergoing PCI from January 1999 to December 2000 at a tertiary care center in Detroit, MI, were followed up. End points studied included either all cause mortality collected from Social Security Death Index or first hospital admission after the index procedure due to myocardial infarction(MI), congestive heart failure(CHF), and revascularization (PCI or coronary artery bypass graft surgery).

RESULTS

African-Americans undergoing PCI had significant differences in baseline cardiovascular co-morbidity and were more likely to present with acute myocardial infarction than Caucasians. On Kaplan Meier survival analysis and log rank test, each ethnic group had equivalent survival for cumulative end points upto 6-month follow-up, however longer follow-up to 5 year was characterized by lower survival rate in African Americans compared to Caucasians (41% vs. 54%, log rank P 0.01). After adjustment for potential confounders, AA ethnicity (Adjusted HR 1.62, 95% CI 1.01-1.28, P 0.04) remained a predictor of adverse cardiac outcome (Death/MI/CHF) at five-year follow-up (Cox regression propensity adjusted hazard analysis).

CONCLUSIONS

African American patients undergoing PCI had unfavorable baseline cardiovascular characteristics but comparable short-term outcome compared to whites. However, at 5-year follow-up, African Americans had worse clinical outcome, higher incidence of acute myocardial infarction, congestive heart failure and significantly lower long-term survival.

Severity of coronary artery disease in obese patients undergoing coronary angiography: "obesity paradox" revisited

BACKGROUND

Recent studies have highlighted the existence of an 'obesity paradox' in patients undergoing coronary angiography, i.e., a high body mass Index (BMI) is associated with less severe coronary lesions. We sought to confirm the existence of this phenomenon in the US patient population.

METHODS

Study subjects included 770 consecutive patients (470 men, 428 African-Americans, 212 Caucasians) referred for coronary angiography to a tertiary care center. Duke myocardial jeopardy score, a prognostication tool predictive of 1-year mortality in coronary artery disease (CAD) patients, was assigned to angiographic data. Patients were classified according to their BMI (kg/m2) as normal (21-24), overweight (25-29), obesity class I (30-34), class II (35-39) and class III (40 or above).

RESULTS

Patients in the increasing obesity class had a higher prevalence of diabetes, hypertension and dyslipidemia and were more likely to be women. A negative correlation was observed between BMI and age (R = - 0.15 p < 0.001) as well as between BMI and Duke Jeopardy score (r = - 0.07, p < 0.05) indicating that patients with higher BMI were referred for coronary angiography at a younger age, and had a lower coronary artery disease (CAD) burden. BMI was not an independent predictor of coronary lesion severity on multivariate stepwise linear regression analysis.

CONCLUSION

Obese patients are referred for coronary angiography at an earlier age and have a lower CAD burden lending further credence to the existence of an apparent "obesity paradox". However, obesity per se, after adjustment for comorbidities, is not an independent predictor of severity of coronary artery disease.

Ethnic and sex differences in disease burden in patients undergoing coronary angiography: the confounding influence of obesity

BACKGROUND

Data from cohort studies, predominantly in Caucasians, have identified obesity as a major risk factor for coronary artery disease (CAD), irrespective of sex. In contrast, reports examining the effects of obesity on mortality in African Americans suggest a weak relationship between body mass index (BMI) and mortality, particularly among women. Data correlating body weight with angiographic severity of CAD is sparse in minority populations. We sought to investigate ethnic-sex differences in the influence of obesity on the extent and severity of CAD.

METHODS

We studied 640 patients (66.9% African American) who underwent coronary angiography at a tertiary care center. Cardiovascular risk factor profiles and CAD burden, quantified by the Duke Myocardial Jeopardy scoring system, a validated prognostication tool, were compared across ethnic and sex groups.

RESULTS

Clustering of major cardiovascular risk factors, a higher prevalence of obesity classes II and III, and a statistically significant inverse correlation between BMI and Duke scores were observed among the cohort of African American women. General linear model analysis and stepwise multiple linear regression analysis revealed Duke score to be negatively associated with BMI and higher classes of obesity after adjustment for age and other cardiovascular risk factors in African American women but not in other subgroups.

CONCLUSIONS

The observed inverse relationship between BMI and angiographic severity of CAD in African American women is novel and appears to support prior data on the weak association between BMI and cardiovascular mortality in this subgroup.

Determinants of amount of contrast utilized in patients undergoing percutaneous coronary procedures

OBJECTIVE

To determine predictors of contrast amount during coronary angiography and percutaneous coronary intervention.

BACKGROUND

Contrast-induced nephropathy is a leading cause of hospital-acquired acute renal insufficiency. During percutaneous coronary procedures, contrast amount is a major risk factor incriminated in development of contrast-induced nephropathy.

METHODS

Demographic and procedural details were obtained for consecutive patients undergoing percutaneous coronary procedures between January 2002 and October 2005 (N=962, mean+/-standard error of contrast amount: 216.6+/-3.0 ml) at a tertiary care hospital.

RESULTS

A significant difference (P value <0.05) in unadjusted mean contrast volume was observed between subgroups of percutaneous coronary intervention vs. coronary angiography, patients with a history of coronary artery bypass grafting, patients undergoing additional procedures and multivessel and multisite percutaneous coronary interventions. On General Linear Model analysis, independent predictors (beta coefficient, 95% confidence interval, P value) of increased contrast amount during percutaneous coronary procedures were history of coronary artery bypass grafting (44.4, 30.6-58.2, <0.001), type of coronary procedure (85.2, 73.4-97.0, <0.001 for percutaneous coronary intervention vs. coronary angiography), number of interventions and number of additional procedures performed. Among additional procedures, rotablation, intravascular ultrasound and Angiojet were associated with increased contrast use. No significant independent effect on the contrast amount was observed with percutaneous coronary intervention location (right coronary artery vs. left anterior descending artery vs. circumflex artery) site (ostial vs. proximal vs. mid vs. distal) of percutaneous coronary intervention or with interventions on chronic total occlusions on the contrast amount.

CONCLUSION

Data from our study could guide the coronary angiographer in moderating the volume of contrast utilized as well as assist with the elective planning of complex therapeutic procedures.

VCP/p97 AAA-ATPase does not interact with the endogenous wild-type cystic fibrosis transmembrane conductance regulator

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that is defective in cystic fibrosis. The most common mutation, DeltaF508 CFTR, is retained in the endoplasmic reticulum, retrotranslocated into the cytosol, and degraded by the proteasome. In a proteomics screen to identify DeltaF508 CFTR interacting proteins, we found that valosin-containing protein (VCP)/p97, a Type II AAA ATPase that is a component of the retrotranslocation machinery, binds DeltaF508 CFTR, and this interaction is stabilized by proteasomal inhibition. Since wild-type (WT) CFTR has been reported to be inefficiently processed during biogenesis with as much as 75% of the newly synthesized protein degraded by the proteasome, we examined the VCP interaction in Calu-3, T-84, and 16HBE, three epithelial cell lines that endogenously express WT CFTR. The results indicate that when WT CFTR processing is efficient, as demonstrated in Calu-3 cells, VCP does not interact. Interestingly, overexpression of recombinant WT CFTR in Calu-3 cells results in inefficient processing and VCP interaction, demonstrating that CFTR processing efficiency and the VCP interaction are tightly coupled. Furthermore, induction of ER stress and activation of the unfolded protein response result in inefficient processing of WT CFTR in Calu-3 cells and promote the WT CFTR-VCP interaction. The results support the hypothesis that components of the retrotranslocation machinery such as VCP do not interact with CFTR in epithelial cells that endogenously express WT CFTR, since under normal conditions the processing of the WT protein is efficient.

Efficient intracellular processing of the endogenous cystic fibrosis transmembrane conductance regulator in epithelial cell lines

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent protein kinase A-activated chloride channel that resides on the apical surface of epithelial cells. One unusual feature of this protein is that during biogenesis, approximately 75% of wild type CFTR is degraded by the endoplasmic reticulum (ER)-associated degradative (ERAD) pathway. Examining the biogenesis and structural instability of the molecule has been technically challenging due to the limited amount of CFTR expressed in epithelia. Consequently, investigators have employed heterologous overexpression systems. Based on recent results that epithelial specific factors regulate both CFTR biogenesis and function, we hypothesized that CFTR biogenesis in endogenous CFTR expressing epithelial cells may be more efficient. To test this, we compared CFTR biogenesis in two epithelial cell lines endogenously expressing CFTR (Calu-3 and T84) with two heterologous expression systems (COS-7 and HeLa). Consistent with previous reports, 20 and 35% of the newly synthesized CFTR were converted to maturely glycosylated CFTR in COS-7 and HeLa cells, respectively. In contrast, CFTR maturation was virtually 100% efficient in Calu-3 and T84 cells. Furthermore, inhibition of the proteasome had no effect on CFTR biogenesis in Calu-3 cells, whereas it stabilized the immature form of CFTR in HeLa cells. Quantitative reverse transcriptase-PCR indicated that CFTR message levels are approximately 4-fold lower in Calu-3 than HeLa cells, yet steady-state protein levels are comparable. Our results question the structural instability model of wild type CFTR and indicate that epithelial cells endogenously expressing CFTR efficiently process this protein to post-Golgi compartments.